Bullet jackets are mostly vest-shaped. It consists of a clothing cover and a bulletproof layer. Clothing should be made of chemical fiber fabric and covered with protective bulletproof layer; The bulletproof layer is made of metal, glass fiber reinforced plastic and other materials, which can make the warhead and shrapnel bounce off and release the impact kinetic energy, thus playing a protective role. Body armor has certain ability to prevent direct projectiles and body armor pieces, and it has a good protective effect on human chest and abdomen.